Re: qemu/m68k

Hi Greg,
Greg Ungerer wrote,

> Hi Waldemar,
> 
> On 15/08/14 00:18, Waldemar Brodkorb wrote:
> >Hi uClinux hackers,
> >
> >I am trying to build a Linux System for Qemu/m68k to do runtime
> >testing of a uClibc spin-off called uClibc-ng.
> >(http://www.uclibc-ng.org)
> >
> >I am really a newbie regarding MMU-less Linux systems, so don't be
> >to critical ;)
>
> I don't know what happened to the CVS there. Not sure if it will
> be coming back.

May be yu could remove the dead links? Do you have access to the
webserver? Or you could setup a git repository for it? 
I can help with it, if you need admin or technical information about
it.
 
> Anyway, I can give you a starting point that works for me. I have
> used the tools I generated at:
> 
>   http://www.uclinux.org/pub/uClinux/m68k-elf-tools/tools-20101118/m68k-uclinux-tools-20101118.sh
> 
> for a couple of years now. They generate working systems that
> run on real hardware and also under qemu. The source for generating
> those tools is there in that same directory:
> 
>  http://www.uclinux.org/pub/uClinux/m68k-elf-tools/tools-20101118/
> 
> I only use it for building Coldfire targets.
> 
> That is building the uclinux-dist:
> 
>   http://www.uclinux.org/pub/uClinux/dist/
> 
> That is a 3.10 kernel, but you can take any linus kernel and use
> that with the same result. The uClibc in there may have some changes
> over a stock 0.9.33.
> 
> A good place to start debugging these types of user space problems
> is with the kernel trace option of flat files. So use the flthdr tool
> to enable the kernel trace flag (-k) on the generated flat files,
> then build you rootfs with those. Then at least you can see where
> you app is in RAM.

Yeah, thanks a lot. Kernel trace helped. I got further booting up
the system. I am not really sure, what my problem was, but now I get
to the first shell (busybox hush). I think my elf2flt setup was
br0ken or -msep-data in CFLAGS fixed it.
My bootlog with a strace output of hush:
http://openadk.org/coldfire.txt

Do you have a suggestion why I get a segfault after first executed
command? Similar behaviour Thomas Petazzoni have seen, while he was
trying to run buildroot in Qemu/m68k. See here:
http://lists.busybox.net/pipermail/buildroot/2012-April/052585.html

BTW: I compiled uClinux, but the result does not start in Qemu.
I used CONFIG_DEFAULTS_FREESCALE_M5208EVB to configure it.
Is there a reason you use -m5307 for gcc, instead of -m5208?

Without the kernel patch from Thomas you get no output.
Without the Qemu patch from Thomas you get:
qemu-system-m68k -nographic -kernel image.elf                                                                                                                                                 
qemu: hardware error: mcf_intc_write: Bad write offset 28

With kernel and qemu patch I get:
Linux version 3.10.0-uc0 (wbx@kop-brodkorbw) (gcc version 4.5.1 (GCC) ) #3 Fri Aug 15 19:52:04 CEST 2014
uClinux/COLDFIRE(m520x)
COLDFIRE port done by Greg Ungerer, [email protected]
...
qemu: hardware error: mcf_fec_read: Bad address 0x1c4

Disabling FEC ethernet driver gets me too:
uclinux[mtd]: probe address=0x401e91b8 size=0x0
uclinux[mtd]: set ROMfs to be root filesystem
Creating 1 MTD partitions on "ram":
0x000000000000-0x000000000000 : "ROMfs"
mtd: partition "ROMfs" is out of reach -- disabled
TCP: cubic registered
NET: Registered protocol family 17
end_request: I/O error, dev mtdblock0, sector 2
EXT2-fs (mtdblock0): error: unable to read superblock
VFS: Cannot open root device "(null)" or unknown-block(31,0): error
-5
Please append a correct "root=" boot option; here are the available
partitions:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(31,0)

Which version of Qemu are you using to bootup uClinux?

Thanks in advance
 Waldemar

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